/sbin/fstrim reporting enormous numbers [SOLVED]

% sudo fstrim -v /home
/home: 105964507136 bytes were trimmed

That is >98 GB which I find hard to believe. My entire /home partition is only 100 GB and it only contains 500 MB of files. I have it mounted in /etc/fstab with discard as well. Can someone explain that output to me?

EDIT: HEADSMACK! After consulting the manpage it would appear that fstrim does not trim partial use blocks, it trims ALL blocks not currently in use, so that figure does make sense.